Tone amplifier for sound-reproducing apparatus



April'15, 1930. F. WILHELM ET A1,. 1,754,538

TONE AMPLIFIER FOR SOUND REPRODUCING APPARATUS Filed Feb. 1a, 1926 i gllmlll or'apanwA .722 veniarx:

Mal/er paratus such as membranes, phonographs,

Patented Apr. 15, 1930 nm'rso STATES PATENT OFFICE v v FRITZ WILHELM, 0F BERLIN-HALENSEE, AND KARL J'OHANN M'U'LLER, OF BERLIN- GRUNEWALD, GERMANY; SAID WILHELM ASSIGNOB TO SAID MU'LLER TONE AMPLIFIER FOR SOUND-REPItODUCING APPARATUS Application filed February 18, 1926, Serial No. 89,148, and in Germany February 23, 1925.

Our invention "relates to improvements in tone amplifiers for sound reproducing apelectrical. sound converting apparatus and the like, and more particularly in apparatus of the type having resonance bodies disposed at the outer end of the horn connected with the sound reproducing member. The object of the improvements is to provide an apparatus of this type by means of which tonesof' any character are reproduced with their natural characteristics, body and volume, and by means of which the-most delicate'tones of music made by many instruments and singing are reproduced. In our improved amplifier clear sounds are produced which appear to emanate from a point outside the horn. e

have found that even the music of wind-1nstruments is reproduced in a pure way. i

With this object in view our invention con sists in disposing a member, preferably in the form of a hollow 'cone within the horn and adjacent to the membrane, and rigidly connecting the said member by a substantially rectilinear rod with a diaphragm disposed with its plane substantially perpendicularly of the axis of the horn, the saidmember being freely supported within the horn,

preferably on the said rod. In one embodiment of the invention we provide a wfill or flange at the outer end-of the horn, so that a diaphragm of air is produced between the said wall or flange and the diaphragm. The diaphragm is provided with apertures permitting the passage of the sounds produced by the diaphragm.

For the purpose of explaining the invention an example embodying the same has been illustrated in the accompanying drawing showing a sectional elevation of the horn and the amplifier.

I In the example shown in the figure the apparatus comprises a sound box 8 of ordinary construction and a horn 1 having a tubular neck 2. At its outer end the horn 1 is made integral with a wall or flange 6' and at the front of the said wall or flange there is a diaphragm 5 in the form of a foraminated plate disposed perpendicularly of the axis of I and natural the horn. To the diaphragm 5 a rod 4 is connected which extends rearwardly therefrom and axially of the horn, and which carries a sound collecting member 3 in the form of a hollow cone, said sound collectirig member being located in front of the tubular neck 2. Between the wall 6 and the diaphragm 5 a source of sound such as a, body 7 of air is included which provides a resonappe body. The sound box is shown as being one of the electromagnetic type.

within the horn are reproduced, and the sounds are not spoilt within the horn. For

example in a phonograph when usingonly the horn 1, the noise prodiiced by the stylusis distinctly heard, while with my improved amplifier the said noise is hardly perceptible.

The delicate soft tones referred to are reproduced effectively because the. ultimately produced sound results not only from the magnification of the sound coming from the sound box by the horn but furthermore results from the vibration of the diaphragm 5 activated by the sound collected in the small member 3. In the absence of the collecting member 3, the delicate soft tones are suppressed on their way through the horn" b the louder tones or sounds. When the soun collector 3 is present, the delicate tones are {aransferred to the diaphragm 5 and are not ost. 1 V i We wish it to be understood that our invention is not limited to the relative position that in some cases the horn may be entirely omitted.

The sound box, which is diagrammatically shown in the drawings, can be of the electromagnetic type or of the type wherein a needle or stylus mechanically vibrates a diaphragm, that is, the ordinarily gramophone type.

We claim:

1. A sound reproducing apparatus, comprising a sound reproducing member, a

sound collecting member located adjacent said sound reproducing member, a rectilinear rod carrying said collecting member, and an apertured diaphragm member connected with said rod at a point away from said collecting member and disposed transversely of said rod.

2. A sound reproducing apparatus, comprising a sound reproducing member, a horn disposed in front thereof, an apertured diaphragm disposed at the outer end of the said horn and with its plane transversely of the axis of said horn, a rectilinear rod secured to said apertured diaphragm and extending therefrom into the horn to a point adjacentsaid sound reproducing member, and a sound collecting member in the form of a hollow cone having its cavity at the side of said sound reproducing member and carried at the inner end of sald rod.

3. A sound reproducing apparatus, com- I prising a sound reproducing member, a horn disposed in front thereof, an apertured diaphragm disposed at the outer end of the said horn and with its plane transversely of the axis of said horn, a rectilinear rod secured to said apertured diaphragm and extending therefrom into the horn to a point adjacent said sound reproducing member. and a sound collecting member carried at the inner end of said rod and out of contact with said horn.

4. A sound reproducing apparatus, comprising a sound reproducing member, a horn disposed in front thereof and having a flange at its outer end, an apertured diaphragm disposed at the outer end of the said horn and with its plane transversely of the axis of said horn, a rectilinear rod secured to said apertured diaphragm and extending therefrom into the horn to a point adjacent said sound reproducing member, and a sound collecting member carried at the inner end ofsaid rod.

In testimony whereof we have signed our names to this specification.

FRITZ WILHELM. KARL JOHANN ULLER. 

